The present invention relates to intravascular prostheses for remodeling an extravascular anatomical structure. In one application, the present invention relates to a mitral annuloplasty and cardiac reinforcement device which is transluminally implantable in the coronary sinus.
Dilated cardiomyopathy occurs as a consequence of many different disease processes that impair myocardial function, such as coronary artery disease and hypertension. The left ventricle enlarges and the ejection fraction is reduced. The resulting increase in pulmonary venous pressure and reduction in cardiac output cause congestive heart failure. Enlargement of the mitral annulus and left ventricular cavity produce mitral valvular insufficiency. This in turn, causes volume overload that exacerbates the myopathy, leading to a vicious cycle of progressive enlargement and worsening mitral regurgitation.
According to recent estimates, more than 79,000 patients are diagnosed with aortic and mitral valve disease in U.S. hospitals each year. More than 49,000 mitral valve or aortic valve replacement procedures are performed annually in the U.S., along with a significant number of heart valve repair procedures.
Various surgical techniques have been developed to repair a diseased or damaged valve. One repair technique which has been shown to be effective in treating incompetence, particularly of the mitral and tricuspid valves, is annuloplasty, in which the effective size of the valve annulus is contracted by attaching a prosthetic annuloplasty ring to the endocardial surface of the heart around the valve annulus. The annuloplasty ring comprises an inner substrate of a metal such as stainless steel or titanium, or a flexible material such as silicone rubber or Dacron cordage, covered with a biocompatible fabric or cloth to allow the ring to be sutured to the heart tissue. The annuloplasty ring may be stiff or flexible, may be split or continuous, and may have a variety of shapes, including circular, D-shaped, C-shaped, or kidney-shaped. Examples are seen in U.S. Pat. Nos. 4,917,698, 5,061,277, 5,290,300, 5,350,420, 5,104,407, 5,064,431, 5,201,880, and 5,041,130, which are incorporated herein by reference.
Annuloplasty rings may also be utilized in combination with other repair techniques such as resection, in which a portion of a valve leaflet is excised, the remaining portions of the leaflet are sewn back together, and a prosthetic annuloplasty ring is then attached to the valve annulus to maintain the contracted size of the valve. Other valve repair techniques in current use include commissurotomy (cutting the valve commissures to separate fused valve leaflets), shortening mitral or tricuspid valve chordae tendonae, reattachment of severed mitral or tricuspid valve chordae tendonae or papillary muscle tissue, and decalcification of the valve leaflets or annulus. Annuloplasty rings may be used in conjunction with any repair procedures where contracting or stabilizing the valve annulus might be desirable.
Although mitral valve repair and replacement can successfully treat many patients with mitral valvular insufficiency, techniques currently in use are attended by significant morbidity and mortality. Most valve repair and replacement procedures require a thoracotomy, usually in the form of a median sternotomy, to gain access into the patient""s thoracic cavity. A saw or other cutting instrument is used to cut the sternum longitudinally, allowing the two opposing halves of the anterior or ventral portion of the rib cage to be spread apart. A large opening into the thoracic cavity is thus created, through which the surgical team may directly visualize and operate upon the heart and other thoracic contents. Alternatively, a thoracotomy may be performed on a lateral side of the chest, wherein a large incision is made generally parallel to the ribs, and the ribs are spread apart and/or removed in the region of the incision to create a large enough opening to facilitate the surgery.
Surgical intervention within the heart generally requires isolation of the heart and coronary blood vessels from the remainder of the arterial system, and arrest of cardiac function. Usually, the heart is isolated from the arterial system by introducing an external aortic cross-clamp through a sternotomy and applying it to the aorta to occlude the aortic lumen between the brachiocephalic artery and the coronary ostia. Cardioplegic fluid is then injected into the coronary arteries, either directly into the coronary ostia or through a puncture in the ascending aorta, to arrest cardiac function. The patient is placed on extracorporeal cardiopulmonary bypass to maintain peripheral circulation of oxygenated blood.
Of particular interest in the present application are techniques for the repair and replacement of the mitral valve. The mitral valve, located between the left atrium and left ventricle of the heart, is most easily reached through the wall of the left atrium, which normally resides on the posterior side of the heart, opposite the side of the heart that is exposed by a median sternotomy. Therefore, to access the mitral valve via a sternotomy, the heart is rotated to bring the left atrium into an anterior position. An opening, or atriotomy, is then made in the right side of the left atrium, anterior to the right pulmonary veins. The atriotomy is retracted by means of sutures or a retraction device, exposing the mitral valve adjacent to the atriotomy. One of the previously identified techniques may then be used to repair or replace the valve.
An alternative technique for mitral valve access has been used when a median sternotomy and/or rotational manipulation of the heart are inappropriate. In this technique, a thoracotomy is made in the right lateral side of the chest, usually in the region of the fourth or fifth intercostal space. One or more ribs may be removed from the patient, and other ribs near the incision are retracted outward to create a large opening into the thoracic cavity. The left atrium is then exposed on the posterior side of the heart, and an atriotomy is formed in the wall of the left atrium, through which the mitral valve may be accessed for repair or replacement.
Using such open-chest techniques, the large opening provided by a median sternotomy or right thoracotomy enables the surgeon to see the mitral valve directly through the left atriotomy, and to position his or her hands within the thoracic cavity in close proximity to the exterior of the heart for cannulation of the aorta and/or coronary arteries to induce cardioplegia, manipulation of surgical instruments, removal of excised tissue, and introduction of an annuloplasty ring or a replacement valve through the atriotomy for attachment within the heart.
Mitral valve surgery, including mitral annuloplasty, is usually applied to patients with intrinsic disease of the mitral apparatus. As described above, these patients may have scarring, retraction, tears or fusion of valve leaflets as well as disorders of the subvalvular apparatus. Definitive repair requires direct visualization of the valve.
Patients who develop mitral regurgitation as a result of dilated cardiomyopathy do not have intrinsic mitral valve disease. Regurgitation occurs as the result of the leaflets being moved back from each other by the dilated annulus. The ventricle enlarges and becomes spherical, pulling the papillary muscles and chordae away from the plane of the valve and further enlarging the regurgitant orifice. In these patients, correction of the regurgitation does not require repair of the valve leaflets themselves, but simply a reduction in the size of the annulus and the sphericity of the left ventricle.
Mitral annuloplasty without repair of the leaflets or chordae has been shown to be effective in patients with dilated cardiomyopathy who are refractory to conventional medical therapy. Bolling and coworkers have operated on a cohort of such patients with New York Heart Association Class III and IV symptoms. Average symptom severity decreased from 3.9 preoperatively to 2.0 after surgery. Hemodynamics and ejection fraction improved significantly. Other investigators have achieved similar results as well. However, the morbidity, risks and expense of surgical annuloplasty are very high in patients with cardiomyopathy and congestive heart failure. Thus, a variety of new techniques for the treatment of congestive heart failure are being explored as adjuncts to drug therapy.
Several cardiac restraint devices have been described. U.S. Pat. No. 5,702,343 to Alfemess discloses a cardiac reinforcement device that is applied as a jacket over the epicardium in order to limit diastolic expansion. However, this requires an open chest operation to implant and does not directly affect the diameter of the mitral annulus. Another approach is disclosed in U.S. Pat. No. 5,961,440 to Schweich, et al., in which tension members are placed through opposite walls of the heart such that they span the ventricle. Less invasive and xe2x80x9cminimallyxe2x80x9d invasive techniques for valve repair and replacement continue to evolve, both on a stopped heart and on a beating heart. These techniques may provide some benefits over open chest procedures, but they are still attended by significant morbidity and mortality risks.
A need therefore remains for methods and devices for treating mitral valvular insufficiency, which are attended by significantly lower morbidity and mortality rates than are the current techniques, and therefore would be well suited to treat patients with dilated cardiomyopathy. Optimally, the procedure can be accomplished through a percutaneous, transluminal approach, using simple, implantable devices which do not depend upon prosthetic valve leaflets or other moving parts.
The invention according to one mode is a medical system with a medical device for remodeling a tissue structure adjacent to a body space that is defined at least in part by a tissue wall in a patient. The medical device has a prosthesis that in a first configuration having a first shape is adapted to be delivered into and positioned at least in part within the body space. The prosthesis is thereafter adjustable within the body space to a second configuration having a second shape that is adapted at least in part to exert a force from within the body space onto the adjacent tissue structure in order to remodel the adjacent tissue structure.
According to one beneficial mode of this aspect wherein the adjacent tissue structure has a wall that circumscribes a space having a diameter, the prosthesis when adjusted from the first configuration to the second configuration within the body space is adapted to compress the adjacent tissue structure to thereby reduce its diameter.
The invention according to another aspect is a medical system with a medical device for remodeling an extravascular tissue structure adjacent to a vessel in a patient. The device has a prosthesis that in a first configuration having a first shape is adapted to be delivered into and positioned at least in part within the vessel. The prosthesis is thereafter adjustable within the vessel to a second configuration having a second shape and is adapted to thus exert a force from within the vessel onto the extravascular tissue structure in order to remodel the extravascular tissue structure.
The invention according to another aspect is a medical system with a medical device for remodeling a mitral valve annulus from within a coronary sinus in a patient. The prosthesis is adapted to be positioned in the first configuration at least in part within a coronary sinus and is adapted to remodel a mitral valve annulus adjacent to the coronary sinus when the prosthesis is located at least in part within the coronary sinus and is adjusted to the second configuration. This aspect is particularly beneficial for use in performing mitral valve annuloplasty and treating mitral valve insufficiency.
According to one highly beneficial mode for these various system aspects of the invention just provided, the prosthesis is an elongate body that extends between proximal and distal ends.
The following are further beneficial embodiments and related applications for this mode with respect to a an elongate body for use according to the aspect of the mitral valve remodeling aspect of the invention. Such further embodiments are also generally considered to be beneficially applicable to the other medical system aspects just described for the invention with respect to the prostheses constructed for remodeling operation generally from within a body space or more specifically from within a vessel, respectively, and in particular without limitation with respect to the mode wherein the respective prosthesis is an elongate body. The following embodiments and applications are considered to be independently beneficial, and are not generally considered mutually exclusive or reliant unless expressly described as such.
In one such further embodiment, the elongate body is adapted to be permanently implanted in the patient at least in part within the coronary sinus in the second configuration in order to provide chronic remodeling of the mitral valve annulus.
In another further embodiment, the device further includes a guidewire tracking member such as a guidewire lumen that is adapted to track over a guide wire in order to position the elongate body within the coronary sinus.
According to another further embodiment, the elongate body is selectively adjustable between the first and second configurations while the elongate body is located at least in part within the coronary sinus. The elongate body is adapted to be temporarily implanted at least in part within the coronary sinus in the second configuration for temporary remodeling of the mitral valve annulus and to be thereafter removed from the coronary sinus in the first configuration.
In still another further embodiment, the elongate body within the coronary sinus comprises a substantially similar length between the first and second configurations.
In still another further embodiment, the elongate body within the coronary sinus is relatively non-expandable while the elongate body is adjusted between the first and second configurations. In another further embodiment, the elongate body within the coronary sinus is relatively non-compressible while the elongate body is adjusted between the first and second configurations.
According to a further embodiment, the elongate body has a length between its respective proximal and distal ends that is less than about 10 cm.
In yet a further embodiment, the device further includes a lock for retaining the elongate body in the second configuration at least in part within the coronary sinus.
In yet a further embodiment, in the second configuration the second shape for the elongate body at least within the coronary sinus defines an arc.
In a further embodiment, the device further includes an anchor for retaining the elongate body at least in part within the coronary sinus. In one application, the anchor is provided at a region along a distal portion of the elongate body. In another application, the anchor provides a friction enhancing surface for engaging a wall of the coronary sinus. In another application, the anchor may have at least one barb for piercing a wall of the coronary sinus.
In further applications of the anchor embodiment, the anchor may be provided at the proximal or distal end of the elongate body, or multiple anchors may be provided. One such application provides a proximal anchor that is adapted to be positioned outside of the coronary sinus and against a wall of the right atrium in order to anchor the elongate body at least in part within the coronary sinus. Another such application is a distal anchor that is adapted to be positioned within the great cardiac vein when the elongate body is located at least in part within the coronary sinus.
In still a further embodiment, a forming element is secured to the elongate body at a point of attachment and that is moveable relative to the elongate body in order to adjust the elongate body within the coronary sinus between the first and second configurations.
In one highly beneficial application of this embodiment, the forming element between the point of attachment and the proximal end of the elongate body is substantially circumferentially confined by the elongate body. This may be achieved in a further beneficial example by providing the forming element within a substantially tubular wall or other radially confining housing of the elongate body.
In another highly beneficial application, the forming element has a proximal extension that extends proximally from the elongate body and externally of the patient when the elongate body is located at least in part within the coronary sinus, and the elongate body within the coronary sinus is adjustable within the coronary sinus from the first configuration to the second configuration by manipulating the proximal extension outside of the patient.
In another application wherein an anchor is provided for retaining at least a portion of elongate body within the coronary sinus, and the axial length of the elongate body between the anchor and the point of attachment of the forming element to the elongate body is within the range of from about 2 cm to about 8 cm. In still another application, an annuloplasty zone is provided on a proximal portion of the body that is adapted to be positioned within the coronary sinus for annuloplasty via the coronary sinus, and an anchor zone is provided on a distal portion of the body. The forming element is attached to the body between a mid-point of the annuloplasty zone and a mid-point of the anchor zone, such that force imparted from the forming element at the point of attachment with respect to the proximal end of the body deflects at least a portion of the annuloplasty zone into an arcuate configuration.
In still another particularly beneficial application of the forming element embodiment, the elongate body is adjustable from the first configuration to the second configuration principally by applying a force from the forming element to the elongate body.
In one more detailed application, wherein the elongate body is adjustable from the first configuration to the second configuration principally by transmitting an axial force from the forming element onto the elongate body relative to the longitudinal axis of the embodiment. In still further detail to this application, the elongate body may be adjustable from the first configuration to the second configuration in response to proximal retraction of the forming element. In another regard, the elongate body may be movable from the first configuration to the second configuration in response to distal advancement of the forming element. In the alternative or in addition to these axial force applications, the forming element may be adapted to adjust the elongate body from the first configuration to the second configuration at least in part by providing a rotational force along at least a portion of the forming element. In one regard, the forming element according to this rotational application may include a rotational force transmission member coupled to an axial force transmission member via a rotational coupler such that rotational forces are converted to axial forces to deflect the elongate body.
In a particularly beneficial further application of the forming element embodiment, the elongate body is adapted to be uncoupled in the second configuration from at least a portion of the forming element as a permanent implant located at least in part within at least the coronary sinus. This may be accomplished by adapting the forming element to be severed while the elongate body is positioned at least in part within the coronary sinus in the second configuration. In one regard, a cutting tool may be provided that is adapted to cut the forming element while the elongate body is positioned at least in part within the coronary sinus. In another regard, the forming element includes proximal and distal members that are detachably engaged in a manner that allows for force transmission from outside the body of the patient to an attachment point to the elongate body, and also for the members to be uncoupled to leave the elongate body and distal member within the patient as a device implant.
In another particularly beneficial further application of the forming element embodiment, the medical device further includes a lock that is adjustable between disengaged and engaged configurations. The disengaged configuration allows the forming element to be moveable relative to the elongate body in order to adjust the elongate body from the first configuration to the second configuration at least in part within the coronary sinus. The engaged configuration engages the forming element to substantially fix the forming element relative to the elongate body when the elongate body is in the second configuration at least in part within the coronary sinus. In a particular application that is highly beneficial for selective adjustment of the elongate body between first and second configurations, the lock is selectively adjustable between the engaged and disengaged configurations. In another beneficial application, locking and/or unlocking tools may also be provided in order to adjust the lock from the disengaged configuration to the engaged configuration, or visa versa, respectively.
In another further beneficial embodiment of the medical system aspect of the invention, a deployment system is provided that cooperates with the elongate body in order to deliver the elongate body or prosthesis in the respective first configuration and shape to the desired location for subsequent operation for tissue remodeling. In one particularly beneficial further detailed embodiment, the deployment system includes at least in part a delivery member that is coupled to the elongate body or prosthesis and is adapted to advance the elongate body or prosthesis into the coronary sinus.
The invention according to another aspect is a method for providing a medical device for use in treating a patient from within a vein that is associated with the patient""s heart. The method according to this aspect includes providing an array of medical devices, each having a prosthesis or elongate body that is adjustable in-situ from a first configuration having a first shape to a second configuration having a second shape. Each elongate body of each medical device of the array is constructed to have a unique size relative to the elongate bodies of the other medical devices of the array. This method aspect also includes choosing the medical device from the array at least in part based upon a known measurement for a vein that is associated with the patient""s heart. A comparison between the measurement of the vein with the unique size for the elongate body of the chosen medical device provides indicia that the unique size is appropriate for being delivered in the first configuration into the patient""s respective vein and for being adjustable within the vein from the first configuration to the second configuration in order to remodel the mitral valve annulus from within the vein.
According to one mode of this aspect, the medical device is chosen at least in part based upon a known measurement for a coronary sinus. According to another mode wherein the vein has a central axis, the known measurement comprises at least one of: a length of at least a portion of the vein, a radius of curvature of the vein along the central axis, and a diameter of the vein across the central axis.
This aspect may be further modified according to another aspect of the invention to include providing the array of devices such that each device is constructed to have at least one unique geometry relative to the elongate bodies of the other medical devices. This method aspect further includes choosing the medical device from the array at least in part based upon a known measurement for a parameter associated with at least one of (i) a valve associated with the patient""s heart, and (ii) a vessel associated with the patient""s heart.
A beneifical mode of this aspect allows the medical device to be chosen from the array at least in part based upon a known measurement for a geometric parameter associated with at least one of the mitral valve and the coronary sinus. With respect to choosing the medical device at least in part based upon a known measurement for a geometric parameter associated with the mitral valve, such geometric parameter may be directly or indirectly associated with a mitral valve annulus of the mitral valve, and may in one particular further embodiment be a diameter of the mitral valve annulus.
There is provided in accordance with one aspect of the present invention, a method of treating mitral valvular insufficiency. The method comprises the steps of tranvenously advancing a prosthesis into the coronary sinus, and deploying at least a portion of the prosthesis within the coronary sinus to reduce the diameter of the mitral annulus. Although deployment can be accomplished in an open surgical procedure, the method preferably further comprises the step of percutaneously accessing the venous system prior to the transluminally advancing step. The venous system may be accessed by one of the internal jugular, subclavian, or femoral veins. Preferably, the deploying step further includes the step of advancing the prosthesis from a first configuration for transluminal implantation to a second configuration to apply pressure to the wall of the coronary sinus and thereby reduce and/or restrain the diameter of the mitral valve annulus.
In accordance with another aspect of the present invention, there is provided a method of performing transluminal mitral annuloplasty. The method comprises the steps of providing a catheter which carries a prosthesis, and percutaneously inserting the catheter into the venous system. The prosthesis is transluminally advanced into the coronary sinus, and deployed in the coronary sinus to influence the size of the mitral valve annulus. Preferably, the prosthesis is caused to exert a compressive force on the mitral valve annulus.
The compressive force of one embodiment is generated by a bias in the prosthesis. In an alternate embodiment, the compressive force is generated by tightening the prosthesis around the mitral valve annulus following the transluminally advancing step. The tightening step may be accomplished by axial movement of a tightening element with respect to the prosthesis.
In accordance with a further aspect of the present invention, there is provided a method of providing a therapeutic compressive force against a tissue structure which is distinct from a vessel wall. The method comprises the steps of positioning a device in the vessel, and exerting a force against the wall of the vessel to exert a force against an extravascular tissue structure. Preferably, the positioning step is accomplished percutaneously. In one application, the extravascular tissue structure comprises the mitral valve annulus. Thus, the present invention provides a method of performing annuloplasty of the mitral valve, comprising positioning a prosthesis in the venous sinus.
In accordance with a further aspect of the present invention, there is provided a method of treating a mitral valve. The method comprises the steps of providing an elongate flexible vascular implant, having a first attachment site spaced axially apart from a second attachment site. The first attachment site is transluminally advanced through the coronary sinus and coronary venous system to form the implant into an open loop. The open loop is reduced in size to place tension on the coronary sinus, and the first attachment site is attached to the second attachment site to close the loop and retain tension on the coronary sinus.
In accordance with another aspect of the present invention, there is provided a method of treating the heart. The method comprises the steps of advancing an implant through an access site and into a coronary vein such as the coronary sinus. A forming element on the implant is thereafter proximally retracted while resisting proximal movement of the implant, thereby forming the implant into a desired shape. The access site is thereafter closed, leaving the formed implant within the coronary vein.
Preferably, the method further comprises the step of locking the implant into the desired shape prior to the closing step. The method may additionally comprise the step of severing at least a portion of the forming element prior to the closing step.
A further aspect of the invention is a medical system with a transluminally implantable device for limiting diastolic expansion of the left ventricle. This device includes an elongate body having a proximal end and a distal end. A first attachment site is provided proximate the distal end of the elongate body and a second attachment site proximate the proximal end of the elongate body. The first and second attachment sites are adapted to be secured together. In one mode of this aspect, the elongate body is flexible a locking clip is provided for securing the ends. The body adapted to loop through the coronary venous system, and the locking clip is adapted to cinch onto the proximal end and distal end of the flexible elongate body until a requisite amount of tension is produced to limit diastolic expansion of the left ventricle.